Resistant starch may replace wheat flour for biscuits

Substituting wheat flour for resistant starch may be an easy way for formulators to boost the health profile of a product without affecting taste or acceptance, says a new study from Spain.

Up to 40 per cent of the wheat flour in a short dough biscuit could be replaced by resistant starch without detrimentally affecting the taste, sweetness and overall acceptance, according to results published in LWT – Food Science and Technology.

Researchers led by Susana Fiszman from the Instituto de Agroquímica y Tecnología de Alimentos (CSIC) in Valencia note that their findings show the “good potential of a resistant starch rich ingredient for developing fibre-rich biscuits with the aim of developing products that increase dietary fibre intake by substituting this ingredient for part of the flour in the formulation”.

Starches can be divided into three groups: rapidly digestible starch (RDS, digested within 20 minutes), slowly digestible starch (SDS, digested between 20 and 120 minutes), and resistant starch (RS). The latter is not digested but is fermented in the large intestine and has 'prebiotic' properties.

Resistant starch can be found naturally in cold cooked potatoes, pasta and rice as well as baked beans and lentils. The new study used National Starch’s Hi-maize 260 resistant starch.

Formulation details

Fiszman and her co-workers formulated a range of short dough biscuits with 20, 40, or 60 per cent of the wheat flour replaced. Biscuits with no resistant starch were also formulated as a comparison.

Results showed that replacement of wheat flour at the 20 and 40 per cent levels did not reduce the overall acceptability of the biscuits, compared to the control biscuits. The best results were observed for the lowest level of resistant starch, while the 40 per cent biscuit had slightly reduced acceptability in terms of colour, appearance and texture. These changes did not alter the “overall acceptance”, said the researchers.

“Neither of these two levels significantly reduced the consumption intention,” said the researchers.

Biscuits made by replacing 60 per cent of the wheat flour with resistant starch were not acceptable to the consumers, however.

Fiszman and her co-workers state that the protein-diluting effects of the resistant starch are probably behind the effects. This would change the water content and water-retention capacity of biscuit dough, they said.

Earlier studies have indicated that consumers generally perceive fibre-enriched products as having a dark colour, “so when using an alternative fibre such as the resistant starch, which is white (the final products were not darker), it is advisable to give consumers more information on what these fibres are and thereby provide them with better criteria on which to base their choice”, they added.